Remove tree_magic_mini

It's not exactly well-maintained, has a couple of bugs and obvious
programming mistakes, requires a system-wide shared mime database and
provides no way to detect the absence of said database.

CHANGELOG.md

@@ -12,6 +12,9 @@ To publish a new release run `scripts/release` from the project directory.
 - Move repository back to <https://github.com/lunaryorn/mdcat>.
 - Restore release binaries.
 
+### Removed
+- Support for `tree_magic_mini` for mime-type detection; mdcat now only uses the `file` tool.
+
 ## [0.28.0] – 2022-07-31
 
 ### Changed

Cargo.toml

@@ -12,9 +12,6 @@ license = "MPL-2.0"
 authors = ["Sebastian Wiesner <sebastian@swsnr.de>"]
 edition = "2021"
 
-[features]
-default = ["tree_magic_mini"]
-
 [dependencies]
 ansi_term = "0.12.1"
 anyhow = "1.0.58"
@@ -30,7 +27,6 @@ tracing = { version = "0.1.35", features = ["release_max_level_warn"] }
 tracing-subscriber = { version = "0.3.14", features = ["env-filter"] }
 ureq = { version = "2.5.0", features = ["tls", "native-certs"] }
 url = "2.2.2"
-tree_magic_mini = { version = "3.0.3", optional = true }
 
 [dependencies.syntect]
 version = "5.0.0"

README.md

@@ -74,9 +74,7 @@ Try `mdcat --help` or read the [mdcat(1)](./mdcat.1.adoc) manpage.
 
 ## Requirements
 
-- For image type detection either:
-    - a system-wide [shared mime database](https://www.freedesktop.org/wiki/Specifications/shared-mime-info-spec/), or,
-    - if `mdcat` is built without default features, the `file` tool with support for `--brief` and `--mime-type` flags.
+For image type detection either the `file` tool with support for `--brief` and `--mime-type` flags must be available in `$PATH`.
 
 [Homebrew]: https://brew.sh
 [MacPorts]: https://www.macports.org

src/magic.rs

@@ -6,7 +6,10 @@
 
 //! Magic util functions for detecting image types.
 
+use anyhow::Result;
+use anyhow::{anyhow, Context};
 use mime::Mime;
+use tracing::{event, Level};
 
 /// Whether the given data is SVG data.
 pub fn is_svg(buffer: &[u8]) -> bool {
@@ -19,31 +22,26 @@ pub fn is_png(buffer: &[u8]) -> bool {
 }
 
 fn is_mimetype(buffer: &[u8], mime: &Mime) -> bool {
-    is_mimetype_impl(buffer, mime)
+    get_mimetype_for_buffer_with_file(buffer).map_or_else(
+        |error| {
+            event!(
+                Level::WARN,
+                ?error,
+                "checking for mime type {} failed: {}",
+                mime,
+                error
+            );
+            false
+        },
+        |detected| detected == *mime,
+    )
 }
 
-#[cfg(feature = "tree_magic_mini")]
-fn is_mimetype_impl(buffer: &[u8], expected_type: &Mime) -> bool {
-    tree_magic_mini::match_u8(expected_type.as_ref(), buffer)
-}
-
-#[cfg(not(feature = "tree_magic_mini"))]
-fn is_mimetype_impl(buffer: &[u8], expected_type: &Mime) -> bool {
-    is_mimetype_file(buffer, mime).unwrap_or_else(|error| {
-        event!(Level::WARN, ?error, "checking for {} failed", mime);
-        false
-    })
-}
-
-#[cfg(not(feature = "tree_magic_mini"))]
-fn is_mimetype_file(buffer: &[u8], expected_type: &Mime) -> Result<bool> {
+fn get_mimetype_for_buffer_with_file(buffer: &[u8]) -> Result<Mime> {
     use std::io::prelude::*;
     use std::io::ErrorKind;
     use std::process::*;
 
-    use anyhow::{anyhow, Context, Result};
-    use tracing::{event, Level};
-
     let mut process = Command::new("file")
         .arg("--brief")
         .arg("--mime-type")
@@ -79,7 +77,7 @@ fn is_mimetype_file(buffer: &[u8], expected_type: &Mime) -> Result<bool> {
         let detected_type = stdout
             .parse::<Mime>()
             .with_context(|| format!("Failed to parse mime type from output: {}", stdout))?;
-        Ok(detected_type == *expected_type)
+        Ok(detected_type)
     } else {
         Err(anyhow!(
             "file --brief --mime-type failed with status {}: {}",